The farmers caught sight of a mysterious object（ ）over when they made their way home at dusk.
A、
flying
B、
is flying
C、
flew
D、
has flown
【正确答案】：A
【题目解析】：
本题中已经有谓语动词caught sight of，所以空格处应该要填非谓语，不选BCD，选A。句意：农民们在黄昏回家时看到一个神秘的物体飞过。
The farmers caught sight of a mysterious object（ ）over when they made their way home at dusk.
The farmers caught sight of a mysterious object（ ）over when they made their way home at dusk.
flying
is flying
flew
has flown
本题中已经有谓语动词caught sight of，所以空格处应该要填非谓语，不选BCD，选A。句意：农民们在黄昏回家时看到一个神秘的物体飞过。